One of the fundamental challenges that a business faces is the ongoing need to attract new customers and retain existing customers. The field of marketing has grown to address this challenge, the result of which has been the development of a wide variety of market research methods that can be used to define and evaluate the efficacy of a marketing campaign. These market research methods may include techniques such as use of surveys to evaluate consumer sentiment and advertisement tracking used to evaluate consumer response to a particular campaign. For instance, a print advertisement containing a telephone number may also include an “extension” that any caller will be asked for; such an extension may be correlated with the particular location where the print advertisement was published. As another example, customers may be asked where they heard about an offer or a website as part of the checkout process. Techniques such as these may allow marketers to improve their marketing campaigns and therefore more effectively attract and retain customers.